1. Field of the Invention
The present invention relates generally to medical devices, kits, and methods. More particularly, the present invention relates to systems and procedures for crossing chronic total occlusions in blood vessels with guidewires and subsequently performing angioplasty, atherectomy, stenting, or other treatments.
Cardiovascular disease is a leading cause of mortality worldwide. Cardiovascular disease can take many forms, and a variety of specific interventional and pharmaceutical treatments have been devised over the years with varying levels of success.
A particularly troublesome form of cardiovascular disease results when a blood vessel becomes totally occluded with atheroma or plaque, referred to as a chronic total occlusion. Until recently, chronic total occlusions have usually been treated by performing a bypass procedure where an autologous or synthetic blood vessel is anastomotically attached to locations on the blood vessel upstream and downstream of the occlusion. While highly effective, such bypass procedures are quite traumatic to the patient.
Recently, catheter-based intravascular procedures have been utilized to treat chronic total occlusions with increasing success. Catheter-based intravascular procedures include angioplasty, atherectomy, stenting, and the like, and are often preferred because they are much less traumatic to the patient. Before such catheter-based treatments can be performed, however, it is usually necessary to cross the occlusion with a guidewire to provide access for the interventional catheter. In some instances, crossing the occlusion with a guidewire can be accomplished simply by pushing the guidewire through the occlusion. The guidewire remains in the blood vessel lumen and provides the desired access path. In many cases, however, the guidewire inadvertently penetrates into the subintimal space between the intimal layer and the adventitial layer of the blood vessel as it attempts to cross the occlusion. Once in the subintimal space, it is very difficult and in many cases impossible to direct the guidewire back into the blood vessel lumen. In such cases, it will usually be impossible to perform the catheter-based intervention and other, more traumatic, procedures may have to be employed.
For these reasons, it would be desirable to provide methods, kits, and apparatus which facilitate crossing a chronic total occlusion in a blood vessel with a guidewire. In particular, it would be desirable to provide catheters, guides, or other apparatus which could be used with a conventional or specialized guidewire to direct or redirect the guidewire from the subintimal space back into the blood vessel lumen after the guidewire has entered such space. Such methods and apparatus should be useful in coronary arteries as well as other blood vessels and should be capable of being performed with or without imaging from within or adjacent to the blood vessel. The apparatus for achieving these objective should be of simple construction and be capable of being used in a straight-forward, generally fool-proof manner. At least some of these objectives will be met by the invention described hereinafter.
2. Description of the Background Art
Catheters having side guidewire entry ports spaced proximally from their distal tips are described in U.S. Pat. Nos. 5,464,395; 5,413,581; 5,190,528; 5,183,470; 4,947,864; and 4,405,314. Catheters and methods for forming lateral penetrations through tissue to and from blood vessels past total occlusions are described in U.S. Pat. Nos. 5,443,497; 5,429,144; 5,409,019; 5,287,861; WO 97/13463; and WO 97/13471.